1. Technical Field
This invention pertains to methods and apparatus utilized in surgical procedures involving fixation of soft tissue to bone tissue and, in particular, to a novel method and apparatus for anchoring sutures to bone tissue.
2. Discussion of the Prior Art
As part of various endoscopic or arthroscopic surgical procedures it is necessary to permanently attach a suture to bone tissue. For example, in certain procedures requiring suturing of soft tissue (e.g., muscle, cartilage, tendons, ligaments, etc.) to bone tissue, the suture must be anchored to the bone tissue before suturing can proceed. The prior art includes numerous suture anchors adapted to be secured in pre-drilled holes or tunnels in the bone tissue, and most of these anchors have one or more disadvantageous characteristics. Some prior art suture anchors are required to be hammered into the bone tissue. These anchors are exemplified by U.S. Pat. Nos. 5,102,421 (Anspach, Jr.); 5,141,520 (Goble et al); and 5,100,417 (Cerier et al). Hammering, or impacting as it is often described, has the disadvantage of potential trauma and damage to surrounding bone tissue, and has limited applicability where the location of the bone tunnel is not axially aligned with an arthroscopic portal to permit transmission of the impacting force through an impactor to the anchor.
Some suture anchors are threadedly mounted in the bone tunnel, as exemplified by U.S. Pat. Nos. 5,156,616 (Meadows et al) and 4,632,100 (Somers et al). The screw insertion procedure tends to be time-consuming in that a pilot hole must first be drilled into the bone and then the hole may have to be tapped to receive the screw. If, as sometimes happens, the surgeon determines that the tunnel is not ideally located, the drilling and tapping of another pilot hole becomes necessary, thereby adding further steps to an already lengthy procedure.
Many suture anchors involve an insertion procedure wherein a relative large insertion tool must partially enter the bone tunnel along with the anchor, thereby requiring a larger diameter tunnel than would be necessary for the anchor alone. Examples of such suture anchors are found in U.S. Pat. Nos. 5,037,422 (Hayhurst et al); 4,741,330 (Hayhurst); 4,968,315 (Gatturna) and 4,899,743 (Nicholson et al). Large diameter bone tunnels for receiving suture are undesirable in many applications, particularly where the bone itself is relatively small. In addition to the insertion tool size, some anchors themselves must be so large as to limit the degree to which bone tunnel diameters can be decreased. An example of such an anchor is found in U.S. Pat. No. 5,224,946 (Hayhurst et al).
Most of the foregoing exemplar prior art suture anchors suffer from the disadvantage of being automatically permanently deployed upon insertion into the bone tunnel. Specifically, such anchors typically have permanently projecting resilient barbs, or the like, that are forced into the tunnel and engage the tunnel wall during the insertion procedure, thereby precluding any proximally directed withdrawal movement. Such withdrawal movement is precluded even if the anchor is still engaged by the insertion tool. It sometimes is desirable to fully or partially insert the suture anchor in a bone tunnel and then withdraw it while it is still engaged by the insertion tool. With most prior art anchors there is no possibility of removing the fully or partially inserted anchor; thus, a new tunnel must be drilled and a second anchor inserted. Accordingly, two (or possibly more) anchors may be left at the surgical site, only one of which is functional.